Tunable Fano resonances based on microring resonator with feedback coupled waveguide

Area of Science:

• Photonics
• Nanotechnology
• Materials Science

Background:

• Fano resonance arises from optical interference between narrow and broad spectral features.
• Silicon micro-ring resonators offer compact and efficient photonic functionalities.

Purpose of the Study:

• To experimentally demonstrate a tunable Fano resonance in silicon micro-ring resonators.
• To explore methods for tuning the Fano resonance spectrum.
• To evaluate the device's potential for optical switching and sensing.

Main Methods:

• Fabrication of a silicon micro-ring resonator with a feedback-coupled waveguide on a silicon-on-insulator substrate.
• Utilizing the thermo-optic effect to tune resonator wavelengths.
• Employing free carrier injection to alter waveguide transmission loss.
• Theoretical modeling and analysis using the scattering matrix method.

Main Results:

• Achieved tunable Fano resonance through optical interference of two resonant cavities.
• Demonstrated periodic tuning of the resonance spectrum via thermo-optic effect and free carrier injection.
• Obtained a maximum extinction ratio of 30.8 dB for the Fano resonance.
• Simulation results showed good agreement with experimental data.

Conclusions:

• The proposed silicon micro-ring resonator device enables tunable Fano resonance.
• The device exhibits a high extinction ratio, making it suitable for optical switching and modulation.
• Its sensitivity also positions it as a promising candidate for high-performance biochemical sensing.